1. Field of the Invention
The invention generally relates to a hand operated, portable chuck for dispensing under tension a roll of stretch film wrapping material.
2. Description of the Prior Art
High-cling stretch film is used in many types of packaging operations to wrap together a plurality of items or containers. While such stretch films are commonly used to unify stacks of uniformly shaped boxes or containers, the ability of such stretch film to readily conform to a variety of shapes, and cling to a variety of surfaces, has rendered it useful in unifying such diverse articles as sacks, bales, axe bundles, and even mixed loads of different shaped articles. Such film provides a strong, lightweight and transparent bond between the articles or containers wrapped. Moreover, because such film naturally clings to itself as well as a variety of surfaces, the wrapping operation may be conveniently carried out without the need for adhesives.
In most wrapping operations, the stretch film must be applied under tension if it is to properly cling to and bind together a particular group of articles or containers. To achieve such tension, various types of stretch film wrapping dispensers have been developed.
An ideal portable stretch wrap dispenser would be simple in structure and inexpensive to manufacture, but durable enough so that it rarely required maintenance or replacement. Moreover, from the operator's point of view, such a dispenser should be conveniently installable onto a new roll of stretch film, and easily removable from a spent roll. It should also allow the operator to easily and conveniently apply a broad range of tension onto the stretch film during the wrapping process. Finally, the dispenser should be lightweight, so that a minimum of the operator's energy is wasted in lifting and carrying the body of the dispenser.
None of the portable dispensers in the prior art has satisfied all of the foregoing "ideal" criteria. For example, the hand-held film dispenser disclosed in U.S. Pat. No. 4,166,589 (Hoover et al) is relatively complicated in structure, necessitating the manufacture and assembly of nine separate parts. Moreover, because the wrapping tension is controlled by means of twistable handles, the manual operator of this device may be forced to slow down or stop the wrapping operation whenever a tension adjustment necessitates that he twist one or both of the handles more than once. Finally, the hand-held device disclosed in the Hoover et al patent is relatively large and hence weighty, which will accelerate the muscle fatigue of the operator, who must constantly lift and carry the dispenser during the wrapping operation.
The film wrapping dispenser disclosed in U.S. Pat. No. 4,102,513 (Guard) is similarly complicated in structure, and relatively complicated to fabricate. While the tension control on this dispenser appears somewhat more convenient for the operator to use during a wrapping operation, the device as a whole is again large and weighty. Additionally, the installation of a new roll of stretch film on this device inconveniently requires the operator to unscrew an operating handle through many revolutions.
While the film wrapping dispenser disclosed in U.S. Pat. No. 4,339,022, is somewhat less complicated in structure, this dispenser inconveniently requires a source of pressurized air to power the braking action it may apply to the roll of stretch wrap film during the wrapping operation.
The wrapping dispensers disclosed in U.S. Pat. Nos. 4,179,081 and 4,248,392 (both by Parry) do provide dispensers which are comparatively simple in structure. But even these mechanisms are not without shortcomings. As stated in the specifications of each, the tension-adjusting handgrips of both of these devices must be manufactured to a "close fit" between the grip and the insertable adapter or core which is inserted in the tube that the film is wrapped upon. Such tolerances increase the effort required to manufacture these devices, and hence the cost. Moreover, because these handgrips are formed from a flexible material, they are likely to require periodic replacement due to the high degree of friction between the flexible inner surface of the grip, and the outer surface of the insertable adapters. Finally, because there is little or no mechanical advantage associated with the braking actions of each of these devices, they require a relatively great amount of hand-squeezing by the operator, which is fatiguing.
Clearly, a need exists for a film wrapping dispenser which is simple in structure, inexpensive to manufacture, easy and convenient to use, and which requires a minimum amount of maintenance or replacement.